1. Field of the Invention
The present invention relates to an apparatus and method for the delivery of laser light. More particularly, but not by way of limitation, the present invention relates to an apparatus and method for the delivery of laser light for therapeutic purposes.
2. Background of the Invention
The use of laser light for therapeutic purposes is well known in the art. For some time relatively high power lasers have been used for surgical purposes such as cutting tissue, vaporizing tissue, cauterizing, and the like. More recently, lower power, less focused lasers have been used to stimulate biological tissue rather than destroy tissue. It has been proven that laser light, thus used, may, among other things, reduce or eliminate chronic pain, promote healing of wounds, and reduce inflamation.
Generally speaking, all light striking a biological tissue is either reflected, transmitted, or absorbed. It has been found that the degree to which a particular tissue reflects, transmits, or absorbs light will vary radically with the wavelength of the light applied to the tissue. Not surprisingly, it has also been found that the biological response of a particular tissue will vary radically with the wavelength of the light applied to the tissue. Furthermore the depth to which a given wavelength of light will penetrate a particular tissue is dependent on the degree to which the tissue is transmissive at the given wavelength.
A number of prior art devices have focused on the use of lasers for such treatments having a wavelength in the near infrared range. For example, U.S. Pat. No. 5,445,146 issued to Bellinger discloses the use of a Nd:YAG laser having a fundamental wavelength of 1064 nanometers with a power level between 100 milliwatts and 800 milliwatts. The Nd:YAG laser is traditionally a pumped laser, excited by an external light source. Such lasers are typically rather cumbersome, relatively expensive, and the output power is somewhat difficult to control. In addition, such lasers are only available with light output at specific wavelengths.
U.S. Pat. No. 5,951,596 also issued to Bellinger discloses the use of either the Nd:YAG laser or, alternatively, an Nd:YLF laser producing energy with a wavelength of 1055 nanometers. As with the Bellinger ""146 device, the Bellinger ""596 patent discloses only the use of a pumped laser.
U.S. Pat. No. 5,755,752 issued to Segal discloses the use of a semiconductor laser, specifically an Indium Gallium Arsenide (In:GaAs) diode configured for producing energy having a wavelength in the near infrared range, in the range between 1044 nanometers to 2520 nanometers, preferably at 1064 nanometers. The laser diode is relatively small allowing it to be positioned in a wand. While the Segal ""752 device overcomes some of the limitations of the devices using pumped lasers, it too only delivers a single wavelength of light to the patient.
U.S. Pat. No. 4,930,504 issued to Diamantopoulos et. al., discloses a cluster probe for biostimulation of tissue having an array of monochromatic radiation sources of a plurality of wavelengths wherein two radiation wavelengths simultaneously pass through a single point. Diamantopoulos teaches that when a tissue is simultaneously exposed to multiple wavelengths of a light, a cumulative, and sometimes synergistic, effect is obtained. Diamantopoulos suggests that this effect is based, in part, on the xe2x80x9cmixingxe2x80x9d of photons.
While the Diamantopoulos ""504 device provides a plurality of wavelengths, it does not provide independent exposure control for each wavelength. Thus, the relative exposure, both in terms of relative intensity and relative duration, between the various wavelengths of light is fixed at the time of manufacture of the device.
It has been shown that the response of a particular tissue to an exposure to light varies based on the wavelength, intensity, and duration of the exposure. Thus, while there are advantages realized in delivering multiple wavelengths of light, to achieve the maximum advantage, the exposure to each particular wavelength must be tailored to, among other things: a) the particular tissue receiving treatment; b) the desired depth of penetration into the tissue for each wavelength of light; and c) the degree of stimulation required.
It is thus an object of the present invention to provide a device for the delivery of laser light which provides a plurality of discrete wavelengths of light each of which strikes substantially the same area on a treated tissue.
It is further object of the present invention to provide independent control for each wavelength of light such that the exposure to each wavelength, in terms of both intensity and duration, may be controlled independently from the other wavelengths of light produced.
It is yet a further object of the present invention to provide a power supply for a laser delivery system which provides multiple output channels, each channel being independently controllable.
The present invention provides an apparatus and method for the delivery of laser light in a therapeutic environment which satisfies the needs and alleviates the problems mentioned above. The inventive apparatus provides a plurality of discrete wavelengths of light wherein each wavelength is provided by a laser diode, or a group of laser diodes, and the intensity and duration of the light produced at each wavelength are independent of the intensity and duration of the light produced at other wavelengths.
The inventive apparatus comprises: a console; a plurality of laser diodes housed within the console such that the light emitted by each of the diodes will illuminate the input of an optical waveguide; and a power supply for providing electrical power to each laser diode. The output of the optical waveguide is used to deliver the light to a tissue. Preferably, each diode is configured to emit a different wavelength of light.
For purposes of this invention, the term xe2x80x9clightxe2x80x9d refers to emitted electromagnetic energy (coherent or otherwise) having a wavelength between 100 nanometers and 2600 nanometers. While only a portion of the spectrum is actually visible to the human eye, the entire range exhibits optical properties relevant to the present invention.
Further objects, features, and advantages of the present invention will be apparent to those skilled in the art upon examining the accompanying drawings and upon reading the following description of the preferred embodiments.